Most hosts resolve IP addresses through the Domain Name System (DNS), which is a distributed directory service used to convert domain names into IP addresses. If a host's DNS resolution fails, it may be trying to connect with the wrong server or the server may not be responding.
The Best Snap resolver
When this happens, your host's resolver must make another attempt at resolving the address using other means, such as using ARP (Address Resolution Protocol). One of the main jobs of a resolver is to keep track of which IP addresses are allocated to which hosts by looking up each host's unique MAC address in its ARP cache. This allows hosts to quickly determine which network interface they are connected to and provides a quick way for hosts to find each other when they are part of the same network. However, it can also lead to some problems if the resolver sees an IP address that isn't in the cache. This is called an unknown address, and it can cause problems for hosts that have been configured with static IP addresses. Unknown addresses can also cause problems for DHCP clients that are assigned an IP address from an unknown subnet